Electric attachment plug



ngc.. 3o. 1924. 1,521,142

O. S. WRIGHT-y ELEGTRI C ATTACHMENT PLUG Filed March .2, 1920 Patented Dec. 30, 1924.

OLIVER S. WRIGHT, OF PHILADELPHIA, PENNSYLVANIA.

ELECTRIC ATTACHMENT PLUG.

Application filed March 2, 1920.

To all whom t mcm/ concern.'

Be it known that I, OLIVER S. VRIGHT, a British subject, of Canada, residing in Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented cert-ain new and useful Improvements in Electric Attachment Plugs, whereof the following is a specification, reference being had to the accompanying drawings.

The invent-ion relates to electric attachment plugs suc-h as are useful in association with lamp sockets, wall receptacles and other electrical fittings.

The purpose of the invention is to provide a structure of the above class of such form as to be universally applicable, and which is simple in design, and of few parts so arranged as to be readily disassembled for connecting the leads of the conductor cord.

The invention also comprehends certain other novel structural features which will be better understood from the detailed description which follows.

In the accompanying drawings, Fig. I is an elevation of an attachment plug conveniently embodying my invention.

Fig. II, is an end elevation of the same as viewed from the left of Fig. I; and

Fig. III, is an enlarged fragmentary midsection.

Fig. IV, is a perspective View suggesting the sequence of assembling certain of the elements of the structure.

Figs. V and VI, are fragmentary illustrations on an enlarged scale showing'to better advantage the details of the protective sheath and guide for the conductor cord; and

Fig. VII, is a detail view showing a modified form of insulating handle.

The device as herein represented comprises a handle 1, of insulating material, and of such configuration as to be capable of being readily grasped. The rear end of the handle is expansively recessed in the form of a bifurcation 2, and the remaining portion axially bored as indicated by the numeral 8, for the accommodation of the conductor cord ll. If desired, the grip of the handle may be roughened or serrated as represented at 5, 5. Throughout the eX- tent of the bifurcation of the handle, the conductor cord 4L, is surrounded by a protective sheathing and guide in the form of a wire coil 6, which is appropriately finished Serial I No. 362,875.

at the outer end by a furrule 7. The ferrule is secured by having its inturned end bent about a number of the terminal turns of the coil as clearly shown in Fig. V. It will be noted from this ligure that the cord 4 touches the inner surface of t-he ferrule only, and that a considerable interval exists between the conducto-r and the coil proper. The terminal turns at the opposite end of the coil are forced or sprung into an internal groove 8, in the bore of the handle, and thus effectively anchored. Directly adjacent its anchorage, the coil is reduced through the extent of a few turns as shown at 9 in Fig. VI. Thus it will be seen that the sheath touches the conductor at its ends, so that relative motion between the two may readily take place without excessive wear.

To the forward end of the handle 1, is attached, as an aXifal continuation, a metallic contact shell 10, such attachment being effected by means of integral tongues 11, punched or otherwise offset. and sul'isequently permanently depressed into indentations 12, in t-he handle. Endwise shifting of the shell 10, with respect to the handle is prevented by an annular ridge 18, formed on the latter. At its rear end, the shell is provided with a thread 15, of standard pitch so as to lit ordinary lamp sockets or similar receptacles; this threaded port-ion comprising just a sufhcient number of turns to insure proper seating and contact within the associated socketl without necessitating excessive turning. Directly adjacent its forward end, the shell has an internal ridge formed by a circumferential external depression 16, and the unthreaded portion is slitted at intervals (circumferentially) as at 17, in Figs. I and IV, these provisions being made for purposes which will be presently explained.

- The structure further. comprises a core piece or member 18, of insulating material` having a peripheral j'nojection or shoulder 19, and for the most part received within the shell 10. This core piece is provided with terminal screws 20 and 21, the former of which is centrally disposed in the outer face of said core piece and threaded into a recessed supplemental plate 22. This plate is secured by means of a metallic bushing 23, lining an aperture provided for the passage of the conductor lead 24. The terminal screw 21, to which the lead 25, is

connected, is let into an extension piece 26, attached, in any approved manner, to a metallic band 27, embracing the reduced portion of the core piece adjacent the shoulder 19. This metallic band is secured and fined, both against rotation and endwise shifting upon the core piece, by means of integrally formed tongues or depressions 28, forcedV into indentations 29, in a manner similar to that described in connection with the means for fastening the metallic shell to the handle.. The bandi 27, is formed with a peripheral flare 30, and in` effect constitutes an adjunctive` peripheral projection or shoulder on the core piece 1.8,.in addition to the integral projection19 already mentioned. lhen the parts areassembled as shown in Fig. il., and screwed into the receiving socket, the flaring projection or shoulder 30 engages with the internal ridge 116, of the she-ll 10, to establish electrical contact therewith. When the plug is screwed into the associatedf socket, the two main parts, i. e., the ele ments by which electrical connection is brought about, are forced into effective' contact by virtue of the flare 30, of the contact band 27?, tending to force the shell outward under the wedging action of the taper upon the circumferential ridge 16 of the shell. Bly this construction, any trouble, which might arisefrom the compression of the shell under the action of the thread when screwed into the socket or receptacle, is eliminated. The core piece is maintained in assembled relation to the shell 1'0, with capacit-y for relative rotation, by means of a retainer ringf 31, this retainer ring being provided with an inturned inwardly projecting flange 32, which extends between the peripheral flare 30, of the bandi 27, and the peripheral projection 19, of Jthe core piece. Fromthe above, it will be seen that the elements `19 and 27, are in effect spaced: peripheral' projections on the core piece 18, forming conjointly an interval or circumferential groove for the reception of thel flange 32, ofl the retainer ring 31. The retainer ring 31', is formed at intervals about its circumference with inwardly extending tongues 33, which are adapted to engage within the circumferential depression or groove 16, previously described. 1n assembling, the retainer ring may be readily sprung about the' end of the shell 10 and there secured, byV virtue of the yielding of the latter permitted by the slits 17, previously noted, and with like facility detached or released and removed by compression of the slitted portion of the shell.

In order to prevent the forcible detachment of the conductor leads 24 and 25, from the terminal screws 20 and 21, in the course of ordinary usage, 1 have provided the core piece with an integral extension 35, which is piercedy as at 36, so that said leads may be passed therethrough in crossed relation, before beino' attached. This arrangement serves as an effective anchorage for the conductor cord.

With the above construction, it will be seen, the handle is freely rotatable about the core piece and insertion into a socket or receptacle may be readily effected without twisting the cord. In the course of this op eration the bifurcation serves to permit lateral flexure of the conductor without any undue strains on the attachment plug or'the associated socket, and without offering ren sistance to the turning of the handle.-

1n the modification showny in Fig. V1.1, the expansive recess in the handle 10,A by which free lateral llexure of the conductor cord is permitted, takes the form of a` bell flare as indicated at 11. F ig. VII, also shows an alternative method of securing the shell 4T2'to thehandle. This is accomplished by embedding the inturned edge 43, ofthe shell in the material of the handle during molding of the latter. Int all other respects, the modified structure just described is similar to the embodiment previously. set forth herein and may be used either with, or without the protective sheath.

Having thus described my invention, I claim:

1'. An attachment plug comprising a core piece with carrying terminals for the conductor leads; spaced elements carried by the core piece constituting circumferential guides and a threaded metallic shell about said core piece having an inward-projecting flange operating between the guides, so as to maintain core piece and sliell in assembled relation with capacity for relative rotation.

2. An attachment plug comprising a threaded. metallic shell; a core piece carrying terminals for the conductor leads and having thereon annular contact means. for engagng'the shell to make electrical connection therewith and spaced from the core piece to form an annular recess therebetween; and retainer means detachably secured to the end of said shell, and engaged in said annular recess to maintain core piece and shell in assembled relation with capacity for relative rotation.

An attachment plug comprising a.

threaded metallic shell; core piece therein having a peri heral shoulder carrying terminals for t e conductor leads; Contactv means on said core piece adjacent its shourlder for engaging said shell'to make electrical connection therewith; and retainerv means on said shell engaged between. the aforesaid shoulder and contact means on the core piece to maintain core piece and shell in assembled relation with capacity for relative rotation.

L1. An attachment plug comprising -a han,-

lll() dle of insulating material, and a threaded metallic shell secured to said handle; an insulating core piece Within said shell having a peripheral projection thereon and carrying a spaced element and appropriate terminals for the conductor leads; and a retainer ring detachably secured about the end of said metallic shell and having an in-turned annular flange extending between the aforesaid peripheral projections and the spaced element so as to maintain the core piece and handle in assembled relation With capacity Y for relative rotation.

5. An attachment plug comprising a handle of insulating material and a threaded metallic shell secured to said handle and having an internal circumferential ridge adjacent its outer end; an insulating core piece Within said shell carrying appropriate terminals for the conductor leads; a metallic contact band fixed about said core piece and having a peripheral flare for engaging with the internal circumferential ridge 0f the shell to make electrical connection therewith; and means for maintaining the core pieceV and the shell in assembled relation with capacity for relative rotation.

6. An attachment plug comprising a cylindrical metallic contact shell threaded at one end and having a circumferential depression adjacent its opposite end, a portion of said shell being slitted at intervals circumferentially; an insulating core piece within said shell having an annular projection thereon and carrying a spaced element and appropriate terminals for the conductor leads; and a retainer ring having an inturned flange extending between the aforesaid peripheral projection and the element and integral tongues for engagement in the circumferential depression of said shell;

said shell yielding, by virtue of the slits therein, to permit said tongues to be sprung into its circumferential depression or released therefrom.

7. An attachment plug of the type described, including a core piece having appropriate terminals for conductor leads, a handle freely rotatable relative to the core piece, said handle being axially bored to accommodate a conductor cord and bifurcated at its outer end to permit free lateral flexure oi the conductor cord to the right or left hand, and said bifurcated portions being exterior'- ly roughened to constitute gripping sur faces.

8. An attachment plug of the type described, including a core piece having terminals for electric conductor leads, an insulating handle freely rotatable relative to the core piece, said handle being axially bored to accommodate a conductor cord and bifurcated at its free end to permit flexure of the conductor cord to the right or left hand, said bifurcated portion being exteriorly roughened to constitute. gripping surfaces, and a flexible coiled Wire protective sheath surrounding the conductor throughout the extent of the bifurcated portion of the handle, said sheath having its terminal portion at one end sprung into an internal retaining groove With adjoining coils contracted to seat in a reduced portion of the handle bore.

In testimony whereof, I have hereunto signed my name at Philadelphia, Pennsylvania, this 28th day of February, 1920.

OLIVER S. WRIGHT. Witnesses:

JAMES H. BELL, E. L. FULLERTON. 

